1. Technical Field
The present invention relates to an operation switch device capable of detecting both a touch operation and a pressing operation.
2. Description of the Related Art
Operation switch devices capable of sensing both touching and pressing of an operation switch by a finger or the like are disclosed, for example, in Patent Document 1 (Japanese Patent No. 4438648), Patent Document 2 (JP-T-2010-532030), Patent Document 3 (Japanese Patent No. 4629621), Patent Document 4 (Japanese Patent No. 4594229), and the like.
The operation switch devices described in these patent documents have a structure, in which a sensor section for sensing a touch operation is integrally formed with a switch section for sensing a pressing operation, as a whole.
The sensor section for sensing a touch operation in each of the operation switch devices in Patent Documents 1 to 4 is configured to detect the touch by a finger of a user as a change in capacitance. On the other hand, the switch section for sensing a pressing operation in Patent Documents 1 and 2 uses a dome-shaped electrode, which provides tactile feedback of the pressing operation to a user and which restores itself to its original switch state. The switch section for sensing a pressing operation in Patent Documents 3 and 4 uses an elastically deformable thin skirt-shaped member, which provides tactile feedback of the pressing operation to a user and which restores itself to its original switch state.
FIG. 11 shows an exemplary construction of the operation switch device disclosed in Patent Document 2. The operation switch device includes a capacitive touch screen (capacitive touch sensing device) 101 formed by a flexible board having a conductive layer formed thereon, and a metallic switch dome 102 formed on a printed circuit board 103.
In the operation switch device of FIG. 11, when a user touches the touch screen 101 with a finger 104, the touch screen 101 senses the touch of the finger 104 with a capacitive touch detection system. When the switch dome 102 is depressed by the finger 104 of the user via the touch screen 101, the switch dome 102 provides an on-off signal corresponding to the depression.
FIG. 12 shows an exemplary construction of the operation switch device disclosed in Patent Document 3. The operation switch device includes an operation key 106 disposed so as to be movable in a vertical direction with respect to a device main body 105, a touch detecting electrode 107 embedded in the operation key 106, an electrode section 109 disposed on a printed circuit board 108, and a proximity sensor 110.
The electrode section 109 includes a fixed electrode 111 fixed to the printed circuit board 108 and a movable electrode 112. The movable electrode 112 is coupled to the fixed electrode 111 via electrode flexible sections 113a and 113b that form a thin skirt-shaped member, and is thus movable in the vertical direction. The touch detecting electrode 107 is electrically connected to the movable electrode 112.
The proximity sensor 110 is disposed on the printed circuit board 108. The movable electrode 112 is separated from the proximity sensor 110 by a predetermined distance when the operation key 106 is not depressed. When the operation key 106 is depressed, the movable electrode 112 approaches the proximity sensor 110 according to the depression based on bending displacement of the electrode flexible sections 113a and 113b that form the thin skirt-shaped member.
In the operation switch device of FIG. 12, a high-frequency signal is supplied to the touch detecting electrode 107, and the high-frequency signal is output as a touch detection signal. In the operation switch device, when a user touches the operation key 106 with a finger 104, a capacitance formed between the finger 104 and the touch detecting electrode 107 changes the level of the high-frequency signal supplied to the touch detecting electrode 107. The touch of the finger 104 on the operation key 106 is detected by detecting this level change.
When the movable electrode 112 approaches the proximity sensor 110 due to the depression of the operation key 106, a switch signal corresponding to the depressing operation is output from the proximity sensor 110.